Projector

ABSTRACT

A technology is provided which makes it possible to easily produce an optical component without considerably deteriorating the optical characteristics of the optical component. The optical component includes a glass substrate, an optical member which is connected to the glass substrate, and a connecting layer used to connect a surface of the glass substrate and a surface of the optical member together. The connecting surface of the glass substrate is defined as the surface which passes light processed by the optical component, and has a roughness of approximately 3 nm to approximately 10 nm in terms of the rms value.

BACKGROUND OF THE INVENTION

[0001] 1. Field of Invention

[0002] The present invention relates to an optical component usingglass, and a projector for projecting and displaying an image using theoptical component.

[0003] 2. Description of Related Art

[0004] In a projector, an image is displayed by modulating light whichhas exited from an illumination optical system using, for example, aliquid crystal light valve in accordance with image information (thatis, an image signal), and by projecting the modulated light onto ascreen.

[0005] The above-described projector includes various optical componentsusing glass. For example, in the liquid crystal light valve, an opticalcomponent comprising a polarizer provided on a glass substrate is used.This optical component includes the polarizer and the glass substrate,with adhesive being used to affix the polarizer onto the glasssubstrate. In general, the surface of the substrate is finished to amirror-smooth state in order to prevent scattering of light at thesurface of the substrate.

[0006] However, it is troublesome to produce an optical component suchas that described above. This is because, when the surface of the glasssubstrate is finished to a mirror-smooth state, it is usually necessaryto perform grinding, lapping, and polishing for a long period of time.This problem also exists in various other types of optical componentsusing glass.

[0007] In order to overcome the above-described conventional problem, itis an object of the present invention to provide a technology whichmakes it possible to easily produce an optical component withoutconsiderably deteriorating the optical characteristics of the opticalcomponent.

SUMMARY OF THE INVENTION

[0008] In order to solve at least a part of the above-described problem,in accordance with an exemplary embodiment of the present invention,there is provided an optical component which may consist of:

[0009] a glass substrate;

[0010] an optical member connected to the glass substrate; and

[0011] a connecting layer for connecting a connecting surface of theglass substrate and a connecting surface of the optical member together.

[0012] According to this exemplary embodiment, the connecting surface ofthe glass substrate is defined as the surface which passes therethroughlight which is processed by the optical component, and has a roughnessof approximately 3 nm to approximately 10 nm in terms of the root meansquare value.

[0013] In the optical component according to another exemplaryembodiment, the connecting surface of the glass substrate is formed as arough surface like that described above. However, the glass substrateand the optical member are connected together by covering theprojections and depressions of the rough surface with the connectinglayer. Accordingly, since the scattering of light at the rough surfacecan be reduced by the connecting layer, it is possible to easily producethe optical component without considerably deteriorating the opticalcharacteristics of the optical component.

[0014] In the optical component according to another exemplaryembodiment, it is preferable that the index of refraction of theconnecting layer be approximately 1.2 to approximately 1.5.

[0015] When the index of refraction of the joining layer is in the aboverange, it is substantially the same as the index of refraction of theglass substrate, making it possible to reduce deterioration in theoptical characteristics of the optical component.

[0016] In the optical component according to another exemplaryembodiment, it is preferable that the ratio of the index of refractionof the joining layer to the index of refraction of the glass be fromapproximately 0.8 to approximately 1.2.

[0017] When the ratio of the index of refraction of the connecting layerto that of the glass substrate is in the above range, it is possible toconsiderably reduce deterioration in the optical characteristics of theoptical component.

[0018] In the optical component according to another exemplaryembodiment, the optical member may be a polarizer, or a retardationfilm, or a lens.

[0019] In the optical component according to another exemplaryembodiment, the optical member may be a light-transmissive member whichhas a polarization separation film formed on the connecting surfacethereof.

[0020] In the optical component according to another exemplaryembodiment, the optical member may be a light-transmissive member whichhas a selection film for selecting light of a predetermined wavelengthrange formed on the joining surface thereof.

[0021] Accordingly, various optical components may be connected to theglass substrate.

[0022] In the optical component according to another exemplaryembodiment, the glass substrate may be sapphire glass.

[0023] Since sapphire glass has a relatively high hardness, it isrelatively difficult to finish the surface thereof to a mirror-smoothstate. Therefore, an optical component which uses sapphire glass can bevery easily produced.

[0024] In the optical component according to another exemplaryembodiment, an antireflection film may be formed on a surface of theoptical component which contacts the air and passes therethrough lightwhich is processed by the optical component.

[0025] This makes it possible to prevent reflection at the surface whichcontacts the air and passes light therethrough, so that the opticalcharacteristics of the optical component is improved.

[0026] In accordance with another exemplary embodiment of the presentinvention, there is provided an optical component which may consist of:

[0027] a plurality of first and second glass substrates alternatelydisposed along a predetermined direction;

[0028] connecting layers for connecting connecting surfaces of the firstglass substrates and corresponding connecting surfaces of the secondglass substrates; and

[0029] polarization separation films and reflective films alternatelydisposed at interfaces between the first glass substrates and thecorresponding second glass substrates;

[0030] In this exemplary embodiment, at the interfaces where thepolarization separation films are formed, the connecting surfaces of thefirst glass substrates each have a roughness of approximately 3 nm toapproximately 10 nm in root mean square value, the polarizationseparation films are formed on the corresponding second glasssubstrates, and the connecting layers are formed between thecorresponding polarization separation films and the corresponding firstglass substrates.

[0031] In the optical component according to this exemplary embodiment,the connecting surfaces of the corresponding first glass substrates areformed as rough surfaces. However, the first and second glass substratesare connected together by covering the projections and depressions ofthe rough surfaces with the corresponding connecting layers. Therefore,it is possible to easily produce the optical component withoutconsiderably deteriorating the optical characteristics of the opticalcomponent.

[0032] In accordance with another exemplary embodiment of the presentinvention, there is provided an optical component which may consist of:

[0033] four columnar glass prisms divided at interfaces forming into asubstantially X shape; and

[0034] connecting layers for connecting connecting surfaces of the fourcorresponding columnar glass prisms.

[0035] In this exemplary embodiment, at least two adjacent columnarglass prisms selected from the four columnar glass prisms are such thatthe joining surface of the first columnar glass prism has a roughness ofapproximately 3 nm to approximately 10 nm in root mean square value, thesecond columnar glass prism has a selection film for selecting light ofa predetermined wavelength range formed thereon, and the connectinglayer of the first columnar glass prism is formed between the selectionfilm and the first columnar prism.

[0036] In the optical component according to another exemplaryembodiment, the connecting surface of the selected first columnar glassprism is formed as a rough surface. However, the two columnar glassprisms are connected together by covering the projections anddepressions of the rough surface with the joining layer. Therefore, theoptical component can be easily produced without considerablydeteriorating the optical characteristics of the optical component.

[0037] Various types of projectors may include the optical components ofthe present invention. For example, according to another exemplaryembodiment of the present invention there may be provided a projectorwhich may consist of:

[0038] an illumination optical system which causes an illumination lightbeam to exit therefrom;

[0039] an electro-optical device for modulating the light beam from theillumination optical system in accordance with image information; and

[0040] a projection optical system for projecting the modulated lightbeam obtained by the electro-optical device.

[0041] The optical component of this exemplary embodiment is provided inany one of the illumination optical system, the electro-optical device,and the projection optical system.

[0042] According to another exemplary embodiment of the presentinvention, there may also be provided a projector which may consist of:

[0043] an illumination optical system which causes an illumination lightbeam to exit therefrom;

[0044] an electro-optical device for modulating the light beam from theillumination optical system in accordance with image information; and

[0045] a projection optical system for projecting the modulated lightbeam obtained by the elecro-optical device.

[0046] The illumination optical system of this exemplary embodiment mayconsist of:

[0047] a polarization generation section which causes a predeterminedpolarized light beam to exit therefrom, the polarization generationsection may consist of an optical component for separating the lightbeam incident thereupon into two types of polarized light beams, and aselection retardation film for making one of the two types of polarizedlight beams which exit from the optical component the same as the otherof the two types of polarized light beams.

[0048] According to another exemplary embodiment of this invention,there is provided a projector for projecting and displaying a colorimage, which may consist of:

[0049] an illumination optical system which causes an illumination lightbeam to exit therefrom;

[0050] a color light separation optical system for separating theillumination light beam which has exited from the illumination opticalsystem into light beams of three color components, a first color lightbeam, a second color light beam, and a third color light beam;

[0051] a first electro-optical device, a second electro-optical deviceand a third electro-optical device for generating a first modulatedlight beam, second modulated light beam, and a third modulated lightbeam, respectively, as a result of modulating in accordance with imageinformation the first color light beam, the second color light beam andthe third color light beam separated by the color light separationoptical system;

[0052] a color light synthesizing optical system for synthesizing thefirst modulated light beam, the second modulated light beam and thethird modulated light beam; and

[0053] a projection optical system for projecting the synthesized lightbeams which exit from the color light synthesizing optical system.

[0054] In this exemplary embodiment, an optical component is provided inany one of the illumination optical system, the color light separationoptical system, the first electro-optical device, the secondelectro-optical device, the third electro-optical device, the colorlight synthesizing optical system, and the projection optical system.

[0055] According to another exemplary embodiment of this invention,there is provided a projector for projecting and displaying a colorimage, which may consist of:

[0056] an illumination optical system which causes an illumination lightbeam to exit therefrom;

[0057] a color light separation optical system for separating theillumination light beam which has exited from the illumination opticalsystem into light beams having three color components, a first colorlight beam, a second light beam and a third color light beam;

[0058] a first electro-optical device, a second electro-optical deviceand a third electro-optical device for generating a first modulatedlight beam, a second modulated light beam and a third modulated lightbeam, respectively, as a result of modulating in accordance with imageinformation the first color light beam, the second color light beam andthe third color light beam separated by the color light separationoptical system;

[0059] a color light synthesizing optical system for synthesizing thefirst modulated light beam, the second modulated light beam and thethird modulated light beam; and

[0060] a projection optical system for projecting the synthesized lightbeams which exit from the color light synthesizing optical system.

[0061] In this exemplary embodiment, the third optical component isprovided in either one of the color light separation optical system andthe color light synthesizing optical system.

[0062] Since these projectors include the above-described opticalcomponents, it is possible to easily produce these projectors withoutconsiderably deteriorating the optical characteristics of theprojectors.

BRIEF DESCRIPTION OF THE DRAWINGS

[0063]FIG. 1 illustrates a projector to which the various exemplaryembodiments of the present invention is applied.

[0064]FIG. 2 is an enlarged view of the illumination optical systemshown in FIG. 1.

[0065]FIGS. 3A and 3B illustrate a polarization generation opticalsystem.

[0066]FIG. 4 illustrates the main portion of the projector shown in FIG.1.

[0067]FIG. 5 is an enlarged view of an optical component provided at thelight-incident-surface side of a liquid crystal light valve shown inFIG. 4.

[0068]FIG. 6 is an enlarged view of an optical component provided at thelight-exiting-surface side of a liquid crystal light valve shown in FIG.4.

[0069]FIG. 7 illustrates a graph showing the transmittance ratios ofpieces of sapphire glass having different surface roughness.

[0070]FIG. 8 illustrates a graph showing the transmittance ratios ofoptical components using pieces of sapphire glass having differentsurface roughness.

[0071]FIG. 9 is an enlarged view of a polarization beam splitter arrayprovided in the illumination optical system shown in FIG. 2.

[0072]FIG. 10 illustrates a polarization beam splitter.

[0073]FIG. 11 is an enlarged view of a superimposing lens provided inthe illumination optical system 100 shown in FIG. 2.

[0074]FIG. 12 is an enlarged view of a cross-dichroic prism provided ina color light synthesizing optical system shown in FIG. 4.

[0075]FIG. 13 illustrates a dichroic prism.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0076] A. Overall Structure of Projector

[0077] A description of various exemplary embodiments of the presentinvention will now be given. FIG. 1 illustrates a projector to which anexemplary embodiment of the present invention is applied. A projector1000 includes an illumination optical system 100 including a lightsource device 120, a color light separation optical system 200, a relayoptical system 220, three liquid crystal light valves 300R, 300G, and300B, a cross-dichroic prism 520, and a projection lens 540.

[0078] As shown in FIG. 1, light beams from the illumination opticalsystem 100 are separated into three color light beams, a red light beam(R), a green light beam (G), and a blue light beam (B) at the colorlight separation optical system 200. The separated color light beams aremodulated by their corresponding liquid crystal light valves 300R, 300G,and 300B in accordance with image information. The modulated color lightbeams are each synthesized by the cross-dichroic prism 520 in order toproject and display a color image onto a screen SC by the projectionlens 540.

[0079]FIG. 2 is an enlarged view of the illumination optical system 100shown in FIG. 1. The illumination optical system 100 includes the lightsource device 120, a first lens array 140 and a second lens array 150, apolarization generation optical system 160, and a superimposing lens170. The light source device 120, the first lens array 140, and thesecond lens array 150 are disposed with reference to a light sourceoptical axis 120 ax, whereas the polarization generation optical system160 and the superimposing lens 170 are disposed with reference to asystem optical axis 100 ax. The light source optical axis 120 axcorresponds to the center axis of the light beam which exits from thelight source device 120, whereas the system optical axis 100 axcorresponds to the center axis of the light beam which exits from anoptical element disposed behind the polarization generation opticalsystem 160. As shown in FIG. 2, the system optical axis 100 ax and thelight source optical axis 120 ax are disposed substantially parallel toeach other so as to be displaced from each other by a displacementamount Dp in the x direction. This displacement amount Dp is describedlater. In FIG. 2, an illumination area LA which is illuminated by theillumination optical system 100 corresponds to the liquid crystal lightvalves 300R, 300G, and 300B.

[0080] The light source device 120 is capable of causing substantiallyparallel light beams to exit therefrom. The light source device 120includes a light-emitting tube 122, a reflector 124 having a spheroidalconcave surface, and a collimating lens 126. The light which has exitedfrom the light-emitting tube 122 is reflected by the reflector 124, andthe reflected light is converted by the collimating lens 126 into lightwhich is substantially parallel to the light source optical axis 120 ax.A light source device including a reflector having a paraboloid ofrevolution concave surface may also be used.

[0081] The first lens array 140 includes a plurality of small lenses 142disposed in a matrix arrangement. Each of the small lenses 142 is aplano-convex lens, and has an external shape which is similar to that ofthe illumination area LA (that is, the liquid crystal light valves) whenviewed from the z direction. The first lens array 140 divides thesubstantially parallel light beams which have exited from the lightsource device 120 into a plurality of partial light beams.

[0082] The second lens array 150 includes a plurality of small lenses152 disposed in a matrix arrangement, with the small lenses 152 beingthe same type as the small lenses 142 of the first lens array 140. Thesecond lens array 150 is capable of causing the center axis of each ofthe partial light beams that has exited from the first lens array 140 tobecome substantially parallel to the system optical axis 100 ax; andcausing the image of each small lens 142 of the first lens array 140 tobe formed on the illumination area LA.

[0083] As shown in FIG. 2, the partial light beams which have exitedfrom their corresponding small lenses 142 of the first lens array 140are gathered and concentrated near the second lens array 150, that is,within the polarization generation optical system 160 through the secondlens array 150.

[0084]FIGS. 3A and 3B illustrate the polarization generation opticalsystem 160. FIG. 3A is a perspective view of the polarization generationoptical system 160, whereas FIG. 3B is a portion of a plan view as seenfrom the +y directions. The polarization generation optical system 160includes a light-shielding plate 62, a polarization beam splitter array64, and a selection retardation film 66. The polarization generationoptical system 160 corresponds to the polarization generation section inthe present invention.

[0085] As shown in FIG. 3A, the polarization beam splitter array 64 isconstructed by bonding a plurality of columnar glass substrates 64 cwhich are substantially parallelogrammic in section.

[0086] Polarization separation films 64 a and reflective films 64 b arealternately formed at the interfaces of the glass substrates 64 c. Thepolarization separation films 64 a are dielectric multi-layered films,whereas the reflective films 64 b are either dielectric multi-layeredfilms or metallic films.

[0087] In the structure of the light-shielding plate 62, light-shieldingsurfaces 62 b and open surfaces 62 a are disposed in a stripedarrangement. In the light-shielding plate 62, the light beams incidentupon the light-shielding surfaces 62 b are blocked, whereas the lightbeams incident upon the open surfaces 62 a pass therethrough. Thelight-shielding surfaces 62 b and the open surfaces 62 a are disposed sothat the partial light beams which have exited from the first lens array140 (FIG. 2) are only incident upon the polarization separation films 64a of the polarization beam splitter array 64, and are not incident uponthe reflective films 64 b. More specifically, as shown in FIG. 3B, thecenters of the open surfaces 62 a of the light-shielding plate 62 aredisposed so as to be substantially aligned with the centers of thepolarization separation films 64 a of the polarization beam splitterarray 64. An open width Wp of each open surface 62 a in the x directionis substantially equal to the size of each polarization separation film64 a in the x direction. Here, the light beams which have passed throughthe open surfaces 62 a of the light-shielding plate 62 are only incidentupon the polarization separation films 64 a, and are not incident uponthe reflective films 64 b. The light-shielding plate 62 may consist of aflat, transparent member (such as a glass plate) having alight-shielding film (such as a chrome film, an aluminum film, or adielectric multi-layered film) partly formed thereon. Thelight-shielding plate 62 may also consist of a light-shielding, flatplate, such as an aluminum plate, having open sections formed therein.

[0088] As shown by the solid line in FIG. 3B, the primary light beam(that is, the center axis) of each partial light beam which has exitedfrom the first lens array 140 (FIG. 2) is incident upon itscorresponding open surface 62 a of the light-shielding plate 62 so as tobe substantially parallel to the system optical axis 100 ax. Eachpartial light beam which has passed through its corresponding opensurface 62 a is incident upon its corresponding polarization separationfilm 64 a. Each polarization separation film 64 a divides thecorresponding incident partial light beam into an s-polarized partiallight beam and a p-polarized partial light beam. Here, each p-polarizedpartial light beam passes through its corresponding polarizationseparation film 64 a, whereas each s-polarized partial light beam isreflected by its corresponding polarization separation film 64 a. Eachs-polarized partial light beam reflected by its correspondingpolarization separation film 64 a travels towards its correspondingreflective film 64 b, and is reflected thereby. Here, each p-polarizedpartial light beam which has passed through its correspondingpolarization separation film 64 a, and each s-polarized partial lightbeam reflected by its corresponding reflective film 64 b aresubstantially parallel to each other.

[0089] The selection retardation film 66 is formed by open layers 66 aand λ/2 phase layers 66 b. The open layers 66 a correspond to portionswhere the λ/2 phase layers 66 b are not formed. The open layers 66 a arecapable of passing therethrough linearly polarized light beams incidentthereupon. In contrast, the λ/2 phase layers 66 b function aspolarization conversion elements which convert linearly polarized lightbeams incident thereupon into linearly polarized light beams whosepolarization directions are perpendicular to those of the incidentlinearly polarized light beams. In the embodiment, as shown in FIG. 3B,each p-polarized partial light beam which has passed through itscorresponding polarization separation film 64 a is incident upon itscorresponding λ/2 phase layer 66 b. Therefore, each p-polarized partiallight beam is converted into an s-polarized partial light beam by itscorresponding λ/2 phase layer 66 b, and exits therefrom. On the otherhand, each s-polarized partial light beam reflected by its correspondingreflective film 64 b is incident upon its corresponding open layer 66 a,so that it exits from its corresponding open layer 66 a unchanged. Inother words, the unpolarized partial light beams incident upon thepolarization generation optical system 160 are converted intos-polarized partial light beams and exit therefrom. By disposing the λ/2phase layers 66 b only at the exiting surfaces of the s-polarizedpartial light beams reflected by their corresponding reflective films 64b, the partial light beams incident upon the polarization generationoptical system 160 can also be converted into p-polarized partial lightbeams and be made to exit therefrom. In the selection retardation film66, the λ/2 phase layers 66 b may simply be bonded to the exitingsurfaces of either the p-polarized partial light beams or thes-polarized partial light beams without forming anything at thelocations where the open layers 66 a are formed.

[0090] As shown in FIG. 3B, the centers of the two s-polarized lightbeams which exit from the polarization generation optical system 160 aredisplaced in the +x direction from the center of the unpolarized lightbeam (an s-polarized light beam +a p-polarized light beam) incidentthereupon. The amount of displacement is equal to half a width Wp of thecorresponding λ/2 phase layer 66 b (that is, the size of thecorresponding polarization separation film 64 a in the x direction).Therefore, as shown in FIG. 2, the light source optical axis 120 ax andthe system optical axis 100 ax are displaced from each other by adistance Dp equal to Wp/2.

[0091] The plurality of partial light beams which have exited from thefirst lens array 140 are, as described above, each divided into twopartial light beams by the polarization generation optical system 160,and are converted into substantially one type of linearly polarizedlight beams whose polarization directions are the same. The plurality ofpartial light beams whose polarization directions are the same aresuperimposed upon the illumination area LA by the superimposing lens 170shown in FIG. 2. Here, the distribution of the strength of the lightwhich illuminates the illumination area LA is substantially uniform.

[0092] The illumination optical system 100 (FIG. 1) causes theillumination light (that is, s-polarized light beams) whose polarizationdirections are the same to exit therefrom in order to irradiate theliquid crystal light valves 300R, 300G, and 300B through the color lightseparation optical system 200 and the relay optical system 220.

[0093] The color light separation optical system 200 includes twodichroic mirrors 202 and 204, and a reflective mirror 208, and separatesthe light beams which exit from the illumination optical system 100 intothe three color light beams, the red light beam, the green light beam,and the blue light beam. The first dichroic mirror 202 passestherethrough the red component of the light which has exited from theillumination optical system 100, and reflects the blue and greencomponents. The red light beam R which has passed through the firstdichroic mirror 202 is reflected by the reflective mirror 208 and exitstherefrom towards the cross-dichroic prism 520. The red light beam Rwhich has exited from the color light separation optical system 200passes through a field lens 232 and reaches the liquid crystal lightvalve 300R for red light. The field lens 232 is capable of convertingeach partial light beam which has exited from the illumination opticalsystem 100 into a light beam which is parallel to the center axis of thefield lens 232. Field lenses 234 and 230 disposed adjacent to thelight-incident surface of the liquid crystal light valve 300G and thelight-incident surface of the liquid crystal light valve 300B,respectively, function similarly to the field lens 232.

[0094] Of the blue light beam B and the green light beam G reflected bythe first dichroic mirror 202, the green light beam G is reflected bythe second dichroic mirror 204 and exits from the color light separationoptical system 200 towards the cross-dichroic prism 520. The green lightbeam G which has exited from the color light separation optical system200 passes through the field lens 234, and reaches the liquid crystallight valve 300G for green light. On the other hand, the blue light beamB which has passed through the second dichroic mirror 204 exits from thecolor light separation optical system 200 and impinges upon the relayoptical system 220.

[0095] The blue light beam B incident upon the relay optical system 220passes through light-incident-side lens 222, a relay lens 226,reflective mirrors 224 and 228, and a light-exiting-side lens (that is,a field lens) 230 of the relay optical system 220 in order to reach theliquid crystal light valve 300B for blue light. The relay optical system220 is used for the blue light beam B because the light path for theblue light beam B is longer than the light paths for the red light beamR and the green light beam G. By using the relay optical system 220, theblue light beam B incident upon the light-incident-side lens 222 can betransmitted to the light-exiting-side lens 230 unchanged.

[0096] In accordance with provided image information (that is, imagesignals), the three liquid crystal light valves 300R, 300G, and 300Bmodulate the three corresponding incident color light beams in order togenerate modulated light beams. Each liquid crystal light valve includesa liquid crystal panel and polarizers disposed at thelight-incident-surface side and the light-exiting-surface side of theliquid crystal panel, respectively. The liquid crystal light valves aredescribed in more detail below.

[0097] The cross-dichroic prism 520 synthesizes the three color lightbeams which have passed through and which have been modulated by theircorresponding liquid crystal light valves 300R, 300G, and 300B in orderto produce synthesized light beams representing a color image. In thecross dichroic prism 520, a red light reflective film 521 and a bluelight reflective film 522 are disposed so as to form a substantially Xshape at the interfaces of four right-angled prisms. The red lightreflective film 521 is a dielectric multi-layered film which reflectsred light, while the blue light reflective film 522 is a dielectricmulti-layered film which reflects blue light. The three color lightbeams are synthesized by the red light reflective film 521 and the bluelight reflective film 522 in order to generate synthesized light beamsrepresenting a color image.

[0098] The synthesized light beams generated by the cross dichroic prism520 exit towards the projection lens 540. The projection lens 540projects the synthesized light beams which have exited from thecross-dichroic prism 520 onto the screen SC in order to display thecolor image thereon. The projection lens 540 may be a telecentric lens.

[0099]FIG. 4 illustrates the main portion of the projector 1000 shown inFIG. 1. In FIG. 4, the optical systems starting from the polarizationgeneration optical system 160 up to the cross-dichroic prism 520, shownin FIG. 1, are illustrated, focusing attention on the polarizationdirection. Lenses and the like which are virtually unrelated to thepolarization direction are not illustrated in FIG. 4.

[0100] As shown in FIG. 4, s-polarized light beams exit from thepolarization generation optical system 160.

[0101] As described above, each s-polarized light beam is separated intoa red light beam R, a green light beam G, and a blue light beam B by thetwo dichroic mirrors 202 and 204. In passing through the dichroicmirrors 202 and 204, the polarization direction does not change, so thatthe three color light beams remain as s-polarized light beams.

[0102] The red light beam R of each s-polarized light beam separated bythe first dichroic mirror 202 is reflected by the reflective mirror 208and impinges upon the first liquid crystal light valve 300R. The liquidcrystal light valve 300R includes a liquid crystal panel 301R and twopolarizers (that is, first and second polarizers) 302Ri and 302Rodisposed at the light-incident-surface side and thelight-exiting-surface side of the liquid crystal panel 301R,respectively. A λ/2 phase film 303R is provided at thelight-exiting-surface side of the liquid crystal panel 301R.

[0103] The first polarizer 302Ri is bonded to a first glass substrate307R, while the second polarizer 302Ro and the λ/2 phase film 303R arebonded to a second glass substrate 308R. The polarization axes of thefirst and second polarizers 302Ri and 302Ro intersect at right angles toeach other. The first polarizer 302Ri transmits s-polarized light beamstherethrough, whereas the second polarizer 302Ro transmits p-polarizedlight beams therethrough.

[0104] The s-polarized light beams incident upon the first liquidcrystal light valve 300R pass through the first glass substrate 307R andthe first polarizer 302Ri for transmitting s-polarized light beamsunchanged, and impinge upon the liquid crystal panel 301R. The liquidcrystal panel 301R converts some of the s-polarized light beams incidentthereupon into p-polarized light beams, and only the p-polarized lightbeams exit from the second polarizer 302Ro for transmitting p-polarizedlight beams disposed adjacent to the light-exiting-surface of the liquidcrystal panel 301R. The p-polarized light beams which have exited fromthe second polarizer 302Ro for transmitting p-polarized light beamsimpinge upon the λ/2 phase film 303R through the second glass substrate308R, and are converted into s-polarized light beams by the λ/2 phasefilm 303R, after which the converted s-polarized light beams exit fromthe λ/2 phase film 303R.

[0105] The green light beam G of each s-polarized light beam separatedby the second dichroic mirror 204 impinges upon the second liquidcrystal light valve 300G. The second liquid crystal light valve 300Gincludes a liquid crystal panel 301G, a first polarizer 302Gi fortransmitting s-polarized light beams disposed adjacent to thelight-incident surface of the liquid crystal panel 301G, and a secondpolarizer 302Go for transmitting p-polarized light beams disposedadjacent to the light-exiting surface of the liquid crystal panel 301G.The first polarizer 302Gi and the second polarizer 302Go are bonded to afirst glass substrate 307G and a second glass substrate 308G,respectively. The green light beam G of each s-polarized light beamincident upon the second liquid crystal light valve 300G passes throughthe first glass substrate 307G and the first polarizer 302Gi fortransmitting s-polarized light beams unchanged, and impinges upon theliquid crystal panel 301G.

[0106] The liquid crystal panel 301G converts some of the s-polarizedlight beams incident thereupon into p-polarized light beams, and onlythe p-polarized light beams exit from the second polarizer 302Go fortransmitting p-polarized light beams disposed adjacent to thelight-exiting surface of the liquid crystal panel 301G. The p-polarizedlight beams which have exited from the second polarizer 302Go fortransmitting p-polarized light beams pass through the second glasssubstrate 308G.

[0107] The blue light beam B of each s-polarized light beam separated bythe second dichroic mirror 204 is reflected by the two reflectivemirrors 224 and 228, and impinges upon the third liquid crystal lightvalve 300B. The third liquid crystal light valve 300B includes a liquidcrystal panel 301B, two polarizers (that is, first and secondpolarizers) 302Bi and 302Bo, a λ/2 phase film 303B, a first glasssubstrate 307B to which the first polarizer 302Bi is bonded, and asecond glass substrate 308B to which the second polarizer 302Bo and theλ/2 phase film 303B are bonded. The structure of the third liquidcrystal light valve 300B is the same as the structure of the firstliquid crystal light valve 300R.

[0108] In the three first, second and third liquid crystal light valves300R, 300G, and 300B used in the embodiment, the first polarizers 302Ri,302Gi, and 302Bi for transmitting s-polarized light beams are disposedat the light-incident surface sides of the three corresponding liquidcrystal light valves 300R, 300G, and 300B, whereas the correspondingsecond polarizers 302Ro, 302Go, and 302Bo for transmitting p-polarizedlight beams are disposed at the light-exiting surface sides of the threecorresponding liquid crystal light valves 300R, 300G, and 300B. Here,the liquid crystal alignment states of the liquid crystal panels 301R,301G, and 301B are the same.

[0109] In the embodiment, the first and third liquid crystal lightvalves 300R and 300B are constructed so that the light beams exitingtherefrom are s-polarized light beams, whereas the second liquid crystallight valve 300G is constructed so that the light beams exitingtherefrom are p-polarized light beams, in order to increase theefficiency with which the cross-dichroic prism 520 uses light. Morespecifically, the two reflective films 521 and 522 formed at thecross-dichroic prism 520 reflect s-polarized light beams better thanp-polarized light beams, but transmit p-polarized light beams betterthan s-polarized light beams. Therefore, the two red and blue lightreflective films 521 and 522 are made to reflect s-polarized lightbeams, and to transmit p-polarized light beams therethrough.

[0110] As can be understood from the foregoing description, the first tothird liquid crystal light valves 300R, 300G, and 300B used in theembodiment correspond to first to third electro-optical devices used inthe present invention. In general, although the term electro-opticaldevice used in a narrow sense only refers to the liquid crystal panel ofa liquid crystal light valve, in the specification the termelectro-optical device is used in a wider sense to refer not only to theliquid crystal panel but also to the polarizers, the λ/2 phase plate,and the like.

[0111] B. Optical Component (1)

[0112]FIG. 5 is an enlarged view of an optical component provided at thelight-incident-surface side of the first liquid crystal light valve 300R(FIG. 4). An optical component 410 includes the first polarizer 302Riand the first glass substrate 307R which holds the first polarizer302Ri. The first polarizer 302Ri and the first glass substrate 307R areconnected together at their connecting surfaces by a connecting layerCL. Antireflection films (not shown) for preventing reflection of lightat the interfaces are formed on the surfaces of the optical component410 which contact air and which pass light which is processed by theoptical component 410, that is, the light-incident surface of the firstglass substrate 307R which passes red light R therethrough and thelight-exiting surface of the first polarizer 302Ri.

[0113] As shown in exaggerated form in FIG. 5, one surface Sm of thefirst glass substrate 307R is a specular surface, while the othersurface Sr thereof is a rough surface or a connecting surface which isconnected to the first polarizer 302Ri. As mentioned above, in general,a surface of a glass substrate is finished to mirror-smooth state inorder to minimize scattering of light. The specular surface of the glasssubstrate is usually formed by grinding, lapping, and polishing.

[0114] However, the time required to polish a glass substrate is usuallythe same as the time required to lap glass. Therefore, it is verytroublesome to finish a glass substrate into a mirror-smooth state. Inthe optical component 410 shown in FIG. 5, the first glass substrate307R is used without polishing the joining surface of the first glasssubstrate 307R. Therefore, the optical component 410 can be easilyproduced.

[0115] In general, grinding is a relatively rough smoothing process forforming glass into a predetermined shape with predetermined dimensions,and uses a grindstone such as diamond. Lapping is a smoothing processfor improving the finished state of the surface of the glass substratethat has been ground, and uses abrasive grains such as alumina, siliconcarbide, or diamond grains. Polishing is a smoothing process forproducing a high mirror-finished surface of a glass substrate. Grainswhich are finer than the abrasive grains used in the lapping process,such as cerium oxide grains or colloidal silica grains, are used.

[0116] After the lapping process, the roughness of the surface of theglass substrate, though depending on the abrasive grains used in thelapping process, is usually in a range of approximately 3 nm toapproximately 10 nm in terms of the rms (root mean square) value. On theother hand, after the polishing process, the roughness of the surface ofthe glass substrate is usually in a range of approximately 1 nm toapproximately 2 nm in terms of the rms value. The roughness of thesurface of the glass substrate can be measured using, for example, anon-contact, optical-surface-roughness measuring device. WYKO NT-2000(produced by VEECO) may be used for the non-contact,optical-surface-roughness measuring device. In general, it is possibleto confirm with the naked eye whether any scattering of light at thesurface of the glass substrate after the lapping process. However, it isdifficult to confirm with the naked eye any scattering of light at thesurface of the glass substrate after the polishing process.

[0117] In the specification, rough surface refers to a surface obtainedafter the lapping process, with a roughness of approximately 3 nm toapproximately 10 nm in terms of the rms value. Specular surface refersto a surface after the polishing process, with a roughness ofapproximately 1 nm to approximately 2 nm in terms of the rms value.

[0118] As mentioned above, in the first glass substrate 307R shown inFIG. 5, the first surface Sm is a specular surface that has beenpolished, whereas the second surface Sr is a rough surface that has beenlapped. The rough surface Sr of the first glass substrate 307R is ajoining surface which is connected to the first polarizer 302Ri. Thefirst glass substrate 307R and the first polarizer 302Ri are connectedtogether by covering the projections and depressions of the roughsurface Sr of the first glass substrate 307R with the connecting layerCL. It is preferable that the index of refraction of the joining layerCL be substantially the same as the index of refraction of the firstglass substrate 307R. A material having an index of refraction ofapproximately 1.2 to approximately 1.5 is actually used.

[0119] Here, the first glass substrate 307R and the connecting layer CLmay be considered as an integrally structured glass substrate. In thiscase, scattering of light at the rough surface Sr of the first glasssubstrate 307R virtually does not occur, so that the first glasssubstrate 307R exhibits optical characteristics that are substantiallythe same as those of a glass substrate finished to a mirror-smoothstate. It is preferable that the index of refraction of the connectinglayer CL be such that the ratio of the index of refraction of theconnecting layer CL to that of the glass substrate be in a range ofapproximately 0.8 to approximately 1.2. In this way, the first glasssubstrate 307R can exhibit optical characteristics which are very closeto those of a glass substrate finished to a mirror-smooth state.

[0120] Adhesives, glue, and the like, may be used for the connectinglayer CL having an index of refraction of approximately 1.2 toapproximately 1.5. When a separate device for affixing the first glasssubstrate 307R and the first polarizer 302Ri together is used for theconnecting operation, gel, sol, a liquid, or the like, may be used. Forexample, PHOTO bond 150 (produced by Sunrise MSI) may be used for theconnecting layer CL. The adhesive has an index of refraction ofapproximately 1.474 before curing, and an index of refraction ofapproximately 1.502 after curing.

[0121]FIG. 6 is an enlarged view of an optical component provided at thelight-exiting-surface side of the first liquid crystal light valve 300R(FIG. 4). An optical component 420 includes the second polarizer 302Ro,the λ/2 phase film 303R, and the second glass substrate 308R which holdsthe second polarizer 302Ro and the λ/2 phase film 303R. The secondpolarizer 302Ro and the second glass substrate 308R, and the λ/2 phasefilm 303R and the second glass substrate 308R are connected together attheir corresponding connecting surfaces by corresponding connectinglayers CL. Antireflection films (not shown) for preventing reflection oflight at the interfaces are formed on the surfaces of the opticalcomponent 420 which contact air and pass light which is processed by theoptical component 420, that is, the light-incident surface of the secondpolarizer 302Ro and the light-exiting surface of the λ/2 phase film303R, both of which surfaces pass red light R therethrough.

[0122] In the second glass substrate 308R shown in FIG. 6, a firstsurface Sr1 and a second surface Sr2 are formed as rough surfaces bylapping. The first rough surface Sr1 of the glass substrate 308R isconnected to the second polarizer 302Ro, whereas the second roughsurface Sr2 is connected to the λ/2 phase film 303R. Even in the opticalcomponent 420, the second polarizer 302Ro and the second glass substrate308R, and the λ/2 phase film 303R and the second glass substrate 308Rare connected together, respectively, by covering the projections anddepressions of their corresponding first and second rough surfaces Sr1and Sr2 of the second glass substrate 308R with their correspondingconnecting layers CL. This can considerably reduce scattering of lightat the rough surfaces of the second glass substrate 308R, so that thesecond glass substrate 308R can exhibit optical characteristics whichare substantially the same as those of a glass substrate which finishedto a mirror-smooth state.

[0123] Sapphire glass is used for the first and second glass substrates307R and 308R shown in FIGS. 5 and 6, respectively. Since sapphire glassis relatively hard, it is relatively difficult to finish sapphire glassto a mirror-smooth state. Therefore, when sapphire glass is used for thefirst and second glass substrates 307R and 308R as in the embodiment, itis particularly advantageous to apply the present invention. White sheetglass may be used instead of sapphire glass.

[0124]FIG. 7 illustrates a graph showing the transmittance ratios ofsapphire glass substrates having different surface roughness. The graphshows the transmittance ratios obtained when the sapphire glasssubstrates alone are disposed between a light source and alight-intensity measuring device. The transmittance ratios are measuredwith reference to the light intensity obtained when nothing is disposedbetween the light source and the light-intensity measuring device.Antireflection films are not formed on the surfaces of the sapphireglass substrates used in this experiment.

[0125] A curve C1 indicates the transmittance ratio of a conventionallyused sapphire glass substrate, that is, a sapphire glass substratehaving both surfaces polished. A curve C2 indicates the transmittanceratios of sapphire glass substrates having both surfaces subjected to afirst type of lapping operation.

[0126] A curve C3 indicates the transmittance ratios of sapphire glasssubstrates having both surfaces subjected to a second type of lappingoperation. For each of the curves C2 and C3, two samples are used.

[0127] The roughness of the surfaces of the sapphire glass substrate(curve C1) which have been polished are approximately 1.8 nm in terms ofthe rms values. The roughness of the surfaces of the sapphire glasssubstrates (curve C2) which have been subjected to the first type oflapping operation are approximately 3.4 nm in terms of the rms values.The roughness of the surfaces of the sapphire glass substrates (curveC3) which have been subjected to the second type of lapping operationare approximately 7.6 nm in terms of the rms values. In the first typeof lapping operation, abrasive grains which are finer than those used inthe second type of lapping operation are used.

[0128] As can be seen from the graph shown in FIG. 7, the transmittanceratios of the sapphire glass substrates (curve C2) having both surfacessubjected to the first type of lapping operation and the transmittanceratios of the sapphire glass substrates (curve C3) having both surfacessubjected to the second type of lapping operation are considerablysmaller than the transmittance ratio of the sapphire glass substrate(curve C1) having both surfaces polished. More specifically, thetransmittance ratios of light of approximately 550 nm of the sapphireglass substrates (curve C3) having both surfaces subjected to the secondtype of lapping operation are approximately 5% smaller than that of thesapphire glass substrate (curve C1) having both surfaces polished. Thisis because light is scattered at the rough surfaces that have beenlapped.

[0129]FIG. 8 illustrates a graph of the transmittance ratios of opticalcomponents using sapphire glass substrates having different surfaceroughness. Like the optical component shown in FIG. 6, the opticalcomponents used in this experiment each may consist of a λ/2 phase filmand a polarizer bonded to a sapphire glass substrate through a joininglayer. Antireflection films are formed on the light-incident surface andthe light-exiting surface of each optical component. In the graph shownin FIG. 8, the transmittance ratios are obtained when the opticalcomponents are disposed between a light-intensity measuring device andan illuminating device from which linearly polarized light beams exit.The transmittance ratios are measured with reference to the intensity oflight when nothing is disposed between the illuminating device and thelight-intensity measuring device.

[0130] The optical components are disposed so that almost all of thelinearly polarized light beams which have exited from the illuminatingdevice pass through their corresponding polarizers. The light beamswhich exit from the λ/2 phase films are all detected by thelight-intensity measuring device regardless of the polarization states.

[0131] A curve D1 indicates the transmittance ratio of an opticalcomponent using a sapphire glass substrate having both surfacespolished, and corresponds to the curve C1. A curve D2 indicates thetransmittance ratio of an optical component using the sapphire glasssubstrate having both surfaces subjected to the first type of lappingoperation, and corresponds to the curve C2. A curve D3 indicates thetransmittance ratio of an optical component using the sapphire glasssubstrates having both surfaces subjected to the second type of lappingoperation, and corresponds to the curve C3.

[0132] As can be seen from FIG. 8, the transmittance ratio of theoptical component (curve D2) using the sapphire glass substrate havingboth surfaces subjected to the first type of lapping operation and thetransmittance ratio of the optical component (curve D3) using thesapphire glass substrate having both surfaces subjected to the secondtype of lapping operation are substantially the same as thetransmittance ratio of the optical component (curve D1) using thesapphire glass substrate having both surfaces polished. Morespecifically, the transmittance ratio of light of approximately 550 nmof the optical component (curve D3) using the sapphire glass substratehaving both surfaces subjected to the second type of lapping operationis only approximately 1% less than that of the optical component (curveD1) using the sapphire glass substrate having both surfaces polished.This is because scattering of light at the rough surfaces which havebeen lapped is reduced by the corresponding connecting layers.

[0133] From the graphs illustrated in FIGS. 7 and 8, it can be seen thatthe optical component 420 shown in FIG. 6 including the sapphire glasssubstrate 308R having rough surfaces provides substantially the sameoptical characteristics as those provided when a sapphire glasssubstrate having only specular surfaces is used.

[0134] In the case where a sapphire glass substrate is used, when atleast one of the connecting surfaces is a rough surface such as the tworough surfaces of a sapphire glass substrate which has been subjected tothe same type of lapping and which has a light transmittance ratio ofapproximately 0.8 (80%) when the wavelength is 550 nm, it is possible toobtain substantially the same optical characteristics as those when asapphire substrate both of whose surfaces are specular surfaces areused.

[0135] As can be understood from the foregoing description, theconnecting surface of the first glass substrate 307R of the opticalcomponent 410 shown in FIG. 5 and the connecting surfaces of the secondglass substrate 308R of the optical component 420 shown in FIG. 6 passlight to be processed by the corresponding optical components 410 and420. They have surface roughness of approximately 3 nm to approximately10 nm in terms of the corresponding rms values. The first glasssubstrate 307R is connected to the first polarizer 302Ri by theconnecting layer CL, while the second glass substrate 308R is connectedto the second polarizer 302Ro and the λ/2 phase film 303R by thecorresponding connecting layers CL. This makes it possible to easilyproduce the optical components 410 and 420 without significantlydeteriorating the optical characteristics of the optical components 410and 420.

[0136] In the optical component 410 shown in FIG. 5, the first polarizer302Ri corresponds to an optical member used in the present invention. Inthe optical component 420 shown in FIG. 6, the second polarizer 302Roand the λ/2 phase film 303R correspond to optical members used in thepresent invention.

[0137] C. Optical Component (2)

[0138]FIG. 9 is an enlarged view of the optical component, that is, thepolarization beam splitter array 64 of the illumination optical system100 (FIG. 2). FIG. 9 is an enlarged view of FIG. 3B, in which thelight-shielding film 62 and the selection retardation film 66 areseparated from each other in order to make clear how FIG. 3B correspondswith FIG. 9.

[0139] As shown in FIG. 9, the polarization beam splitter array 64 isconstructed by bonding a plurality of columnar glass substrates whichare substantially parallelogrammic in section. The polarizationseparation films 64 a and the reflective films 64 b are alternatelydisposed at the interfaces of the glass substrates. More specifically,as shown in FIG. 9, a plurality of first glass substrates 64 c 1 and aplurality of second glass substrates 64 c 2 are alternately disposed inthe x direction. The first glass substrates 64 c 1 and the correspondingsecond glass substrates 64 c 2 are bonded together by correspondingconnecting layers CL. In the optical component 64, antireflection films(not shown) for preventing reflection of light are formed on thesurfaces thereof which contact air and pass therethrough light which isprocessed by the polarization beam splitter array 64, that is, thelight-incident surface and the light-exiting surface of each secondglass substrate 64 c 2 which pass an unpolarized light beam (ans-polarized light beam +a p-polarized light beam) and an s-polarizedlight beam, respectively. Antireflection films may also be formed on thelight-incident surface and the light-exiting surface of each first glasssubstrate 64 c 1.

[0140] The first glass substrates 64 c 1 have two rough surfaces whichcorrespond to lapped connecting surfaces Sr1 and Sr2 which are connectedto the corresponding second glass substrates 64 c 2 disposed in the ±xdirections.

[0141] On the other hand, the second glass substrates 64 c 2 have twospecular surfaces which are polished connecting surfaces Sm1 and Sm2which are connected to the corresponding first glass substrates 64 c 1disposed in the ±x directions. The polarization separation films 64 aand the reflective films 64 b are formed, respectively, on the twospecular surfaces Sm1 and Sm2 of their corresponding second glasssubstrates 64 c 2.

[0142] An unpolarized light beam (an s-polarized light beam +ap-polarized light beam) incident upon its corresponding second glasssubstrate 64 c 2 impinges upon its corresponding polarization separationfilm 64 a formed on its corresponding second glass substrate 64 c 2, andis separated into an s-polarized light beam and a p-polarized lightbeam. Here, each s-polarized light beam is reflected by itscorresponding polarization separation film 64 a formed on the specularsurface Sm1 of its corresponding second glass substrate 64 c 2, so thateach s-polarized light beam is not affected by the corresponding roughsurface Sr1 of its corresponding first glass substrate 64 c 1. On theother hand, each p-polarized light beam passes through its correspondingpolarization separation film 64 a and through the rough surface Sr1 ofits corresponding first glass substrate 64 c 1 to exit it. Eachp-polarized light beam is virtually not scattered by its correspondingrough surface Sr1 due to its corresponding connecting layer CL. On theother hand, each s-polarized light beam reflected by its correspondingpolarization separation film 64 a is reflected by its correspondingreflective film 64 b formed on the specular surface Sm2 of itscorresponding second glass substrate 64 c 2, so that each s-polarizedlight beam is unaffected by the corresponding rough surface Sr2 of itscorresponding first glass substrate 64 c 1 disposed in the ±xdirections.

[0143] In the optical component, that is, the polarization beam splitterarray 64 shown in FIG. 9, at the interfaces where the correspondingpolarization separations film 64 a are formed, the connecting surfacesof the first glass substrates 64 c 1 have roughness of approximately 3nm to approximately 10 nm in terms of their corresponding rms values.The polarization separation films 64 a are formed on their correspondingsecond glass substrates 64 c 2. At the interfaces where theircorresponding polarization separation films 64 a are formed, thecorresponding first and second glass substrates 64 c 1 and 64 c 2 areconnected together by the connecting layers CL corresponding thereto. Byconstructing the polarization beam splitter array 64 in theabove-described manner, it is possible to easily produce thepolarization beam splitter array 64 without considerably deterioratingthe optical characteristics of the polarization beam splitter array 64.

[0144] In FIG. 9, at each interface where its corresponding reflectivefilm 64 b is formed, the second connecting surface Sr2 of each firstglass substrate 64 c 1 is rough like each first connecting surface Sr1.However, since light does not pass through any of the second connectingsurfaces Sr2, each second connecting surface Sr2 may be made more rough.

[0145] In FIG. 9, although the polarization beam splitter array 64incorporated in the projector 1000 is illustrated, the present inventionmay also be applied to a polarization beam splitter.

[0146]FIG. 10 illustrates a polarization beam splitter. An opticalcomponent such as a polarization beam splitter 600 may consist of twosubstantially triangular-prism-shaped transmissive members 610 and 620.The first transmissive member 610 and the second transmissive member 620are connected together at their connecting surfaces by a connectinglayer CL, and are formed of glass. An antireflection film (not shown)for preventing reflection of light at the interface is formed on thesurface of the polarization beam splitter 600 which contacts air andwhich passes light which is processed by the polarization beam splitter600.

[0147] The first transmissive member 610 has a rough surface whichcorresponds to a lapped connecting surface Sr which is connected to thesecond transmissive member 620. On the other hand, the secondtransmissive member 620 has a specular surface which is a polishedconnecting surface Sm which is joined to the first transmissive member610. A polarization separation film 600 a is formed on the specularsurface Sm.

[0148] The polarization beam splitter 600 corresponds to a portion ofthe optical component 64 shown in FIG. 9 that has been cut away. Inother words, one block of the optical component 64 shown in FIG. 9including a polarization separation film 64 a formed at an interfacebetween a first glass substrate 64 c 1 and a second glass substrate 64 c2 shown in FIG. 9 corresponds to the optical component 600 shown in FIG.10. Therefore, as in the optical component 64 shown in FIG. 9, thep-polarized light beam separated at the polarization separation film 600a is virtually not scattered as it passes through the rough surface Srwhich is the connecting surface of the first transmissive member 610.

[0149] In the optical component, that is, the polarization beam splitter600 shown in FIG. 10, the connecting surface of the first transmissivemember 610 is defined as the surface which passes light which isprocessed by the optical component, has a roughness of approximately 3nm to approximately 10 nm in terms of the rms value, and is connected tothe second transmissive member 620 having the polarization separationfilm formed thereon by the connecting layer CL. This makes it possibleto easily produce the optical component 600 without considerablydeteriorating the optical characteristics of the optical component 600.The second transmissive member 620 having the polarization separationfilm 600 a formed thereon corresponds to an optical member used in thepresent invention.

[0150] D. Optical Component (3)

[0151]FIG. 11 is an enlarged view of an optical component such as thesuperimposing lens 170 provided in the illumination optical system 100shown in FIG. 2. The superimposing lens 170 includes a glass substrate170 a and a lens 170 b, which are connected together by a connectinglayer CL. An antireflection film (not shown) for preventing reflectionof light at an interface is formed on a surface of the superimposinglens 170 which passes light W which is processed by the superimposinglens 170.

[0152] The lens 170 b is a plano-convex lens formed of resin, with theconvex surface being aspherical. The lens 170 b is formed of resinbecause it is relatively easy to form the lens 170 b into an asphericalshape when resin is used.

[0153] The glass substrate 170 a is a specular surface which correspondsto a polished first surface Sm, and a rough surface which corresponds toa lapped second surface Sr. The rough surface Sr of the glass substrate170 a corresponds to the connecting surface with the lens 170 b. Theglass substrate 170 a and the lens 170 b are connected together bycovering the projections and depressions of the rough surface Sr of theglass substrate 170 a with the connecting layer CL. This substantiallyprevents light from being scattered at the rough surface Sr of the glasssubstrate 170 a.

[0154] In the optical component, that is, the superimposing lens 170shown in FIG. 11, the connecting surface of the glass substrate 170 a isdefined as the surface which passes light which is processed by theoptical component, has a roughness of from approximately 3 nm toapproximately 10 nm in terms of the rms value, and is connected to thelens 170 b by the connecting layer CL. This makes it possible to easilyproduce the superimposing lens 170 without considerably deterioratingthe optical characteristics of the superimposing lens 170. In thesuperimposing lens 170 shown in FIG. 11, the lens 170 b corresponds toan optical member in the present invention.

[0155] The lens 170 b and the connecting layer CL may be integrallyformed. In other words, the lens 170 b may be directly molded onto theglass substrate 170 a using resin. Such an optical component can bemolded by disposing, for example, a mold for molding the lens onto theglass substrate 170 a, and pouring ultraviolet curing resin into themold. Thereafter, the resin is irradiated with ultraviolet rays andhardened. In this case, the resin functions as the lens 170 b and theconnecting layer CL used in the present invention.

[0156] In FIG. 11, the present invention is described as being appliedto the superimposing lens 170 of the illumination optical system 100shown in FIG. 2. However, the present invention may be applied to otherlenses of the illumination optical system 100, such as the first lensarray 140 and the second lens array 150. In addition, the presentinvention may be applied to the projection lens 540 provided in theprojection optical system (FIG. 1).

[0157] E. Optical Component (4)

[0158]FIG. 12 is an enlarged view of an optical component such as thecross-dichroic prism 520 provided in the color light synthesizingoptical system shown in FIG. 4. As mentioned above, the red lightreflective film 521 and the blue light reflective film 522 are formed inthe cross-dichroic prism 520 so as to form a substantially X shape atthe interfaces of the four right-angled prisms. More specifically, thecross-dichroic prism 520 includes four right-angled prisms 511 to 514divided at the interfaces which form a substantially X shape, andconnecting layers CL for connecting the four right-angled prisms attheir connecting surfaces. In the cross-dichroic prism 520 shown in FIG.12, the first to fourth columnar prisms 511 to 514 are formed of glass.In the cross-dichroic prism 520, an antireflection film (not shown) forpreventing reflection of light at the interfaces are formed on thesurfaces which contact the air and which pass light, that is, red lightR, green light G, and blue light B which are processed by thecross-dichroic prism 520.

[0159] The first prism 511 is disposed adjacent to the second prism 512and the fourth prism 514. It has a specular surface Sm1 which is aconnecting surface connected to the second prism 512, and a roughsurface Sr1 which is a connecting surface connected to the fourth prism514. A first red light reflective film 521 a for reflecting red light Ris formed on the specular surface Sm1.

[0160] The second prism 512 is disposed adjacent to the first prism 511and the third prism 513, and has a first rough surface Sr2 a and asecond rough surface Sr2 b, which are connecting surfaces.

[0161] The third prism 513 is disposed adjacent to the second prism 512and the fourth prism 514. It has a specular surface Sm3 which is aconnecting surface connected to the second prism 512, and a roughsurface Sr3 which is a connecting surface connected to the fourth prism514. A first blue light reflective film 522 a for reflecting blue lightB is formed on the specular surface Sm3.

[0162] The fourth prism 514 is disposed adjacent to the first prism 511and the third prism 513. It has a first specular surface Sm4 a which isa connecting surface connected to the third prism 513, and a secondspecular surface Sm4 b which is a connecting surface connected to thefirst prism 511. A second red light reflective film 521 b for reflectingred light R is formed on the first specular surface Sm4 a, whereas asecond blue light reflective film 522 b for reflecting blue light B isformed on the second specular surface Sm4 b.

[0163] The red light R incident upon the first prism 511 is reflected bythe first red light reflective film 521 a and the second red lightreflective film 521 b. When the red light R is reflected by the firstred light reflective film 521 a, it is reflected by the first red lightreflective film 521 a formed on the specular surface Sm1 of the firstprism 511, so that the red light R is unaffected by the rough surfaceSr2 a of the second prism 512. On the other hand, when the red light Ris to be reflected by the second red light reflective film 521 b, itfirst passes through the interface between the first prism 511 and thefourth prism 514. Here, the red light R passes through the rough surfaceSr1 of the first prism 511, but is not scattered at the rough surfaceSr1 due to the connecting layer CL. When the red light R is reflected bythe second red light reflective film 521 b, it is reflected by thesecond red light reflective film 521 b formed on the specular surfaceSm4 a of the fourth prism 514, so that it is virtually unaffected by therough surface Sr3 of the third prism 513. The behavior of the blue lightB with respect to the third prism 513 is similar.

[0164] Green light G incident upon the second prism 512 passes throughthe first red light reflective film 521 a and the second blue lightreflective film 522 b, or passes through the first blue light reflectivefilm 522 a and the second red light reflective film 521 b. In eithercase, the green light G passes through two rough surfaces, but is notscattered at the rough surfaces due to the connecting layers CL.

[0165] In the optical component, that is, the cross-dichroic prism 520shown in FIG. 12, the connecting surfaces of one of two adjacent prisms,that is, a first columnar prism selected from the four columnar prisms511 to 514 have roughness of approximately 3 nm to approximately 10 nmin terms of the rms value. The selection films 521 a, 521 b, 522 a and522 b which select and pass light of a predetermined wavelength rangeare formed at a second columnar prism. The first and second prisms arejoined together by the corresponding connecting layer CL. This makes itpossible to easily produce the cross-dichroic prism 520 withoutconsiderably deteriorating the optical characteristics of thecross-dichroic prism 520.

[0166] In FIG. 12, the cross-dichroic prism 520 is illustrated as acolor light synthesizing optical system provided in the projector 1000.However, the present invention may also be applied to a dichroic prism.

[0167]FIG. 13 illustrates a dichroic prism 550. The dichroic prism 550includes two optical components, that is, color light selection prisms560 and 570. The first color light selection prism 560 reflects redlight R and passes green light G therethrough. The second color lightselection prism 570 passes red light R and green light B which haveexited from the first color light selection prism 560, and passes bluelight B. The three color light beams R, G, and B are synthesized by thetwo color light selection prisms 560 and 570.

[0168] The first color light selection prism 560 includes tworight-angled prisms 561 and 562, which are connected together by aconnecting layer CL. The first right-angled prism 561 includes a roughsurface Sr which is a connecting surface connected to the secondright-angled prism 562. The second right-angled prism 562 includes aspecular surface Sm which is a connecting surface connected to the firstright-angled prism 561. A red light reflective film 551 for reflectingred light R is formed on the specular surface Sm.

[0169] The second color light selection prism 570 similarly includes tworight-angled prisms 571 and 572, which are connected together by aconnecting layer CL. The first right-angled prism 571 includes a roughsurface Sr which is a connecting surface connected to the secondright-angled prism 572. The second right-angled prism 572 includes aspecular surface Sm which is a connecting surface connected to the firstright-angled prism 571. A blue light reflective film 552 for reflectingblue light B is formed on the specular surface Sm.

[0170] The optical component 550 corresponds to the top half portion ofthe cross-dichroic prism 520 shown in FIG. 12 which has been cut away.Therefore, as in the cross-dichroic prism 520 shown in FIG. 12, eachtype of color light is virtually not scattered at the rough surfaces Sror the joining surfaces of the corresponding first right-angled prisms561 and 571.

[0171] As described above, in the optical component, such as the firstcolor light selection prism 560 shown in FIG. 13, the connecting surfaceof the first right-angled prism 561 is defined as the surface whichpasses light which is processed by the optical component, has aroughness of approximately 3 nm to approximately 10 nm in terms of therms value, and is connected to the second right-angled prism 562 by theconnecting layer CL. This makes it possible to easily produce the firstcolor light selection prism 560 without considerably deteriorating theoptical characteristics of the first color light selection prism 560.The structure of the optical component such as, the second color lightselection prism 570 is similar.

[0172] In the first and second color light selection prism 560 and 570shown in FIG. 13, each of the first and second right-angled prisms 561,562, 571, and 572 is formed of white sheet glass. In other words, thefirst right-angled prisms 561 and 571 correspond to glass used in thepresent invention, whereas the second right-angled prisms 562 and 572having formed thereon corresponding selection films 551 and 552 forselecting and passing light of corresponding predetermined wavelengthranges correspond to optical members.

[0173] The cross-dichroic prism 520 shown in FIG. 12 and the dichroicprism 550 shown in FIG. 13 are used as color light synthesizing opticalsystems which synthesize three types of color light. If the direction ofmovement of light is reversed, they can be used as color lightseparation optical systems. More specifically, they can be used as colorlight separation optical systems by causing white light to enter fromthe light-exiting surfaces of the cross-dichroic prism 520 and thedichroic prism 550, and by causing each type of color light to exit fromthe light-incident surfaces of the cross-dichroic prism 520 and thedichroic prism 550. Therefore, these cross-dichroic and dichroic prisms520 and 550 can be used in place of the color light separation opticalsystem 200 shown in FIG. 1.

[0174] The present invention is not limited to the above-describedembodiment and forms, so that the present invention can be carried outin various other forms within the gist of the present invention. Forexample, the following modifications are possible.

[0175] (1) In the above-described embodiment, a polarizer, a λ/2 phasefilm, a lens, a light-transmissive member having a polarizationseparation film formed thereon, a light-transmissive member having aselection film formed thereon, etc., are connected to glass byconnecting layers CL. However, other optical members may be connected tothe glass.

[0176] For example, instead of connecting the λ/2 phase film 303R of thefirst liquid crystal light valve 300R (FIGS. 4 and 6) to glass, a λ/4phase film may be connected to the rough surface Sr2 of the second glasssubstitute 308R. In this case, the λ/4 phase film needs to be providedon the red-light-incident surface of the cross-dichroic prism 520.

[0177] Although, in the polarization beam splitter array 64 shown inFIG. 9, the structure of the present invention is used between the firstand second glass substrates 64 c 1 and 64 c 2, it may be used betweenthe first glass substrate 64 c 1 of the polarization beam splitter array64 and the λ/2 phase layer 66 b of the selection retardation film 66.

[0178] In other words, the present invention is, in general, applicableto an optical component including glass, an optical member which isconnected to glass, and a connecting layer used to connect a surface ofthe glass substrate and a surface of the optical member together. Anykind of optical member may be connected to the connecting surface of theglass substrate as long as the connecting surface is defined as thesurface which passes light and has a roughness of approximately 3 nm toapproximately 10 nm in terms of the rms value.

[0179] (2) Although, in the above-described embodiment, the presentinvention is applied to a transmissive projector, it may also be appliedto a reflective projector.

[0180] Here, a transmissive projector is a type of projector in which anelectro-optical device used as a light-modulation device transmits lightlike a transmissive liquid crystal panel, while a reflective projectoris a type of projector in which an electro-optical device used as alight-modulation device reflects light like a reflective liquid crystalpanel.

[0181] Substantially the same advantages are provided when the presentinvention is applied to a reflective projector as when it is applied toa transmissive projector.

[0182] (3) Although, in the embodiment, the projector 1000 includes aliquid crystal panel as an electro-optical device, it may include amicro-mirror light modulation device instead. For example, a DMD(digital micro-mirror device), which is a trademark of TI, may be usedas the micro-mirror light modulation device. In general, theelectro-optical device used modulates incident light in accordance withimage information.

[0183] (4) Although, in the embodiment, the projector 1000 is describedas displaying a color image, it may also display a monochromatic image.

What is claimed is:
 1. An optical component, comprising: a glasssubstrate; an optical member connected to the glass substrate; and aconnecting layer that connects a connecting surface of the glasssubstrate and a connecting surface of the optical member together, theconnecting surface of the glass substrate being defined as a surfacewhich passes light processed by the optical component, and having aroughness of approximately 3 nm to approximately 10 nm in root meansquare value.
 2. The optical component according to claim 1 , theconnecting layer having an index of refraction of approximately 1.2 toapproximately 1.5.
 3. The optical component according to claim 2 , aratio of an index of refraction of the connecting layer to an index ofrefraction of the glass substrate being approximately 0.8 toapproximately 1.2.
 4. The optical component according to claim 2 , theoptical member being a polarizer.
 5. The optical component according toclaim 2 , the optical member being a retardation film.
 6. The opticalcomponent according to claim 2 , the optical member being a lens.
 7. Theoptical component according to claim 2 , the optical member being alight-transmissive member having a polarization separation film formedon the connecting surface of the optical member.
 8. The opticalcomponent according to claim 2 , the optical member being alight-transmissive member having a selection film that selects light ofa predetermined wavelength range formed on the connecting surface of theoptical member.
 9. The optical component according to claim 1 , theglass substrate comprising sapphire glass.
 10. The optical componentaccording to claim 1 , the optical component having an air contactingsurface which contacts air and which passes therethrough light processedby the optical component, and an antireflection film formed on thesurface air contacting an air contacting surface.
 11. An opticalcomponent, comprising: a plurality of first glass substrates and secondglass substrates alternately disposed along a predetermined direction;connecting layers that connect connecting surfaces of the first glasssubstrates and corresponding connecting surfaces of the second glasssubstrates; and polarization separation films and reflective filmsalternately disposed at interfaces between the first glass substratesand the corresponding second glass substrates, at the interfaces wherethe polarization separation films are disposed, the connecting surfacesof the first glass substrates each have a roughness of approximately 3nm to approximately 10 nm in root mean square value, the polarizationseparation films being formed on the corresponding second glasssubstrates, and the connecting layers being correspondingly formedbetween the polarization separation films and the first glasssubstrates.
 12. An optical component, comprising: four columnar glassprisms divided at interfaces forming into a substantially X shape; andconnecting layers that correspondingly connect connecting surfaces ofthe four columnar glass prisms, at least two adjacent columnar glassprisms being selected from the four columnar glass prisms, such that theconnecting surface of a first of the at least two columnar glass prismshas a roughness of approximately 3 nm to approximately 10 nm in rootmean square value, a second of the at least two columnar glass prism hasa selection film that selects light of a predetermined wavelength rangeformed thereon, and the connecting layer of the first columnar glassprism is formed between the selection film and the first columnar prism.13. A projector, comprising: an illumination optical system that emitsan illumination light beam therefrom; an electro-optical device thatmodulates the light beam from the illumination optical system inaccordance with image information; and a projection optical system theprojects the modulated light beam modulated by the electro-opticaldevice, one of the illumination optical system, the electro-opticaldevice, and the projection optical system including an optical componentwhich comprises a glass substrate, an optical member connected to theglass substrate, and a connecting layer that connects a connectingsurface of the glass substrate and a connecting surface of the opticalmember, and the connecting surface of the glass substrate being definedas a surface which passes therethrough light processed by the opticalcomponent, and having a roughness of approximately 3 nm to approximately10 nm in root mean square value.
 14. The projector according to claim 13, an the index of refraction of the connecting layer being approximately1.2 to approximately 1.5.
 15. The projector according to claim 14 , aratio of an index of refraction of the connecting layer to an index ofrefraction of the glass substrate being approximately 0.8 toapproximately 1.2.
 16. The projector according to claim 14 , the opticalcomponent being disposed on at least one of a light-incident-surfaceside and a light-exiting-surface side of the electro-optical device, andthe optical member being a polarizer.
 17. The projector according toclaim 14 , the optical component being disposed on at least one of alight-incident-surface side and a light-exiting-surface side of theelectro-optical device, and the optical member being a retardation film.18. The projector according to claim 14 , the optical component beingprovided in one of the illumination optical system and the projectionoptical system, the optical component being a lens.
 19. The projectoraccording to claim 13 , the glass substrate is comprising sapphireglass.
 20. The projector according claim 13 , the optical componenthaving an antireflection film formed on a surface of the opticalcomponent which contacts air and passing light processed by the opticalcomponent.
 21. A projector, comprising: an illumination optical systemthat emits an illumination light beam therefrom; an electro-opticaldevice that modulates the light beam from the illumination opticalsystem in accordance with image information; and a projection opticalsystem that projects the modulated light beam modulated by theelectro-optical device, the illumination optical system comprising: apolarization generation section which emits a predetermined polarizedlight beam therefrom, the polarization generation section comprising anoptical component that separates the light beam incident thereupon intotwo types of polarized light beams, and a selection retardation filmthat converts one of the two types of polarized light beams emitted fromthe optical component to another of the two types of polarized lightbeams, the optical component comprising: a plurality of first glasssubstrates and second glass substrates alternately disposed along apredetermined direction; connecting layers that connect connectingsurfaces of the first glass substrates and corresponding connectingsurfaces of the second glass substrates; and polarization separationfilms and reflective films alternately disposed at interfaces betweenthe first glass substrates and the corresponding second glasssubstrates, at the interfaces where the polarization separation filmsare disposed, the connecting surfaces of the first glass substrates eachhaving a roughness of approximately 3 nm to approximately 10 nm rootmean square value, the polarization separation films being formed on thecorresponding second glass substrates, and the connecting layers beingcorrespondingly formed between the polarization separation films and thefirst glass substrates.
 22. A projector that projects and displays acolor image, comprising: an illumination optical system that emits anillumination light beam therefrom; a color light separation opticalsystem that separates the illumination light beam from the illuminationoptical system into light beams of three color components, a first colorlight beam, a second color light beam and a third color light beam; afirst electro-optical device, a second electro-optical device and athird electro-optical device that generate a first modulated light beam,a second modulate light beam and a third modulated light beam,respectively, as a result of modulating in accordance with imageinformation the first color light beam, the second color light beam andthe third color light beam separated by the color light separationoptical system; a color light synthesizing optical system thatsynthesizes the first modulated light beam, the second color light beamand the third modulated light beam; a projection optical system thatprojects synthesized light beams from the color light synthesizingoptical system; and an optical component provided in any one of theillumination optical system, the color light separation optical system,the first electro-optical device, the second electro-optical device, thethird electro-optical device, the color light synthesizing opticalsystem, and the projection optical system, the optical componentcomprising: glass substrate; an optical member connected to the glasssubstrate; and a connecting layer that connects a connecting surface ofthe glass substrate and a connecting surface of the optical membertogether, the connecting surface of the glass substrate being defined asa surface which passes light processed by the optical component, andhaving a roughness of approximately 3 nm to approximately 10 nm in rootmean square value.
 23. A projector that projects and displays a colorimage, comprising: an illumination optical system that emits anillumination light beam to exit therefrom; a color light separationoptical system that separates the illumination light beam from theillumination optical system into light beams having three colorcomponents, a first color light beam, a second color light beam and athird color light beam; a first electro-optical device, a secondelectro-optical device and a third electro-optical device that generatea first modulated light beam, a second modulated light beam and a thirdmodulated light beam, respectively, as a result of modulating inaccordance with image information the first color light beam, the secondcolor light beam and the third color light beam separated by the colorlight separation optical system; a color light synthesizing opticalsystem that synthesizes the first modulated light beam, the secondmodulated light beam and the third modulated light beam; a projectionoptical system that projects the synthesized light beams from the colorlight synthesizing optical system; and an optical component provided inone of the color light separation optical system and the color lightsynthesizing optical system, the optical component comprising fourcolumnar glass prisms divided at interfaces forming a substantially Xshape, and connecting layers that connect connecting surfaces of thefour corresponding columnar glass prisms together, at least two adjacentcolumnar glass prisms selected from the four columnar glass prisms beingsuch that the connecting surface of a first of the at least two adjacentcolumnar glass prisms having a roughness of approximately 3 nm toapproximately 10 nm in root mean square value, a second of the at leasttwo adjacent columnar glass prism having a selection film that selectslight of a predetermined wavelength range formed thereon, and theconnecting layer of the first columnar glass prism being formed betweenthe selection film and the first columnar glass prism.